The present invention relates to a ring-shaped elastic endless crawler which comprises an elongated belt-shaped elastic crawler body, and a plurality of cords disposed in array and embedded in the crawler body so as to extend in a longitudinal direction of the crawler body, in which each of cord protruding portions projecting out from one end of the crawler body, and a corresponding cord protruding portion projecting out from another end of the crawler body are made to overlap each other and the cord protruding portions are entirely subjected to vulcanization processing to thereby form an integrally connected structure.
A conventional rubber crawler 1 will be hereinafter described with reference to FIGS. 1 to 4.
In a manufacturing process of the rubber crawler 1, first, as illustrated in FIG. 3, a semi-manufactured product is formed in which steel cords 3 are made to project out from each of one end la of a crawler body and another end 1b of the crawler body by the same length.
Next, as illustrated in FIG. 4, each of cord protruding portions 3a at the one end 1a of the crawler body, and a corresponding cord protruding portion 3b at the another end 1b of the crawler body are disposed so as to overlap each other. Lines AOxe2x80x94AO, and BOxe2x80x94BO each connecting opposite ends of cord protruding portions, are arranged in parallel in a transverse direction of a belt and extend transversely of an entire width of the belt. For the purpose of facilitating understanding, in FIG. 4, a portion in which cord protruding portions overlap each other is indicated exaggeratively by a thick line.
Due to the cord protruding portions 3a and 3b being entirely subjected to vulcanization processing (heating and filling unvulcanized rubber), an integrated rubber crawler as shown in FIGS. 1 and 2 is completed.
However, the rigidity of the rubber crawler 1 depends on the steel cords 3, and a portion of the crawler body including a region in which steel cords 3 overlap each other, necessarily becomes higher in rigidity (becomes very hard) than a portion of the crawler body not including the region in which the steel cords 3 overlap each other.
Accordingly, when the rubber crawler 1 is used in a state of being fitted around a sprocket or an idler (which are not shown), a state is caused in which a hard portion and a non-hard portion of the rubber crawler 1 are intermittently engaged with each other. As a result, vibration or noise may be unavoidably generated.
Further, the lines AOxe2x80x94AO and BOxe2x80x94BO which form the boundary between a high-rigidity (hard) portion and a nonrigid portion of the rubber crawler 1 are straight lines each extend transversely of an entire width of the crawler body (that is, the belt). Therefore, the rubber crawler 1 is easy to considerably bend with the lines AOxe2x80x94AO and BOxe2x80x94BO substantially as the center.
One object of the present invention is to provide a structure by which a difference in rigidity between a portion of a crawler body including a region in which steel cords overlap each other, and a portion of the crawler body not including the region, can be reduced as far as possible, thereby preventing generation of vibration or noise.
Further, another object of the present invention is to provide a rubber crawler having excellent durability and reliability, in which a boundary between a high-rigidity portion and a nonrigid portion of the rubber crawler is formed characteristically to alleviate occurrence of bending or buckling of the rubber crawler.
In order to solve the above-described problems, an elastic endless crawler of the present invention is a ring-shaped elastic endless crawler which comprises an elongated belt-shaped elastic crawler body, and a plurality of cords disposed in array and embedded in the crawler body so as to extend in a longitudinal direction of the crawler body, in which each of cord protruding portions projecting out from one end of the crawler body and a corresponding cord protruding portion projecting out from the other end of the crawler body are made to overlap each other, and thereafter, are entirely subjected to vulcanization processing to thereby form an integrally connected structure, the elastic endless crawler being characterized in that cord protruding portions at each of the ends of the crawler body are divided into groups such that each group has a protruding length different from those of other groups.
Another elastic endless crawler according to the present invention is characterized in that the entire cord protruding portions at the one end of the crawler body when seen from a direction perpendicular to a belt surface, are formed so as to present a male configuration, and the entire cord protruding portions at the other end of the crawler body are formed so as to present a female configuration.
Still another elastic endless crawler according to the present invention is characterized in that lines each connecting ends of facing cord protruding portions at the ends of the crawler body are disposed so as to have a configuration that is one of terraced, tiered, and crenellated when seen from a direction perpendicular to a belt surface.
A further elastic endless crawler according to the present invention is characterized in that when seen from a direction perpendicular to a belt surface, a portion in which cord protruding portions overlap each other, includes two outlines separated from each other in a longitudinal direction of a belt, and each outline includes a bent line.